#define  _CRT_SECURE_NO_WARNINGS
int Fib(int n)
{
	if (n > 2)
	{
		return Fib(n - 1) + Fib(n - 2);
	}
	else
		return 1;
}

int main()
{
	int n = 0;
	scanf("%d", &n);
	int m = Fib(n);
	printf("%d\n", m);
	return 0;
}